/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.iotdb.confignode.persistence.schema;

import org.apache.commons.io.IOUtils;
import org.apache.iotdb.commons.exception.MetadataException;
import org.apache.iotdb.commons.utils.TestOnly;
import org.apache.iotdb.db.exception.metadata.template.UndefinedTemplateException;
import org.apache.iotdb.db.metadata.template.Template;
import org.apache.iotdb.tsfile.utils.ReadWriteIOUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.*;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.UUID;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.locks.ReentrantReadWriteLock;

public class TemplateTable {

    private static final Logger LOGGER = LoggerFactory.getLogger(TemplateTable.class);

    // StorageGroup read write lock
    private final ReentrantReadWriteLock templateReadWriteLock;

    private final AtomicInteger templateIdGenerator;
    private final Map<String, Template> templateMap = new ConcurrentHashMap<>();
    private final Map<Integer, Template> templateIdMap = new ConcurrentHashMap<>();

    private static final String snapshotFileName = "template_info.bin";

    public TemplateTable() {
        templateReadWriteLock = new ReentrantReadWriteLock();
        templateIdGenerator = new AtomicInteger(0);
    }

    public Template getTemplate(String name) throws MetadataException {
        try {
            templateReadWriteLock.readLock().lock();
            Template template = templateMap.get(name);
            if (template == null) {
                throw new MetadataException(String.format("Template %s does not exist", name));
            }
            return templateMap.get(name);
        } finally {
            templateReadWriteLock.readLock().unlock();
        }
    }

    public Template getTemplate(int templateId) throws MetadataException {
        try {
            templateReadWriteLock.readLock().lock();
            Template template = templateIdMap.get(templateId);
            if (template == null) {
                throw new MetadataException(
                        String.format("Template with id=%s does not exist", templateId));
            }
            return template;
        } finally {
            templateReadWriteLock.readLock().unlock();
        }
    }

    public List<Template> getAllTemplate() {
        try {
            templateReadWriteLock.readLock().lock();
            return new ArrayList<>(templateMap.values());
        } finally {
            templateReadWriteLock.readLock().unlock();
        }
    }

    public void createTemplate(Template template) throws MetadataException {
        try {
            templateReadWriteLock.writeLock().lock();
            Template temp = this.templateMap.get(template.getName());
            if (temp != null) {
                LOGGER.error(
                        "Failed to create template, because template name {} is exists", template.getName());
                throw new MetadataException("Duplicated template name: " + temp.getName());
            }
            template.setId(templateIdGenerator.getAndIncrement());
            this.templateMap.put(template.getName(), template);
            templateIdMap.put(template.getId(), template);
        } finally {
            templateReadWriteLock.writeLock().unlock();
        }
    }

    public void dropTemplate(String templateName) throws MetadataException {
        try {
            templateReadWriteLock.writeLock().lock();
            Template temp = this.templateMap.remove(templateName);
            if (temp == null) {
                LOGGER.error("Undefined template {}", templateName);
                throw new UndefinedTemplateException(templateName);
            }
            templateIdMap.remove(temp.getId());
        } finally {
            templateReadWriteLock.writeLock().unlock();
        }
    }

    private void serialize(OutputStream outputStream) throws IOException {
        ReadWriteIOUtils.write(templateIdGenerator.get(), outputStream);
        ReadWriteIOUtils.write(templateMap.size(), outputStream);
        for (Map.Entry<String, Template> entry : templateMap.entrySet()) {
            serializeTemplate(entry.getValue(), outputStream);
        }
    }

    private void serializeTemplate(Template template, OutputStream outputStream) {
        try {
            template.serialize(outputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private void deserialize(InputStream inputStream) throws IOException {
        ByteBuffer byteBuffer = ByteBuffer.wrap(IOUtils.toByteArray(inputStream));
        templateIdGenerator.set(ReadWriteIOUtils.readInt(byteBuffer));
        int size = ReadWriteIOUtils.readInt(byteBuffer);
        while (size > 0) {
            Template template = deserializeTemplate(byteBuffer);
            templateMap.put(template.getName(), template);
            templateIdMap.put(template.getId(), template);
            size--;
        }
    }

    private Template deserializeTemplate(ByteBuffer byteBuffer) {
        Template template = new Template();
        template.deserialize(byteBuffer);
        return template;
    }

    public boolean processTakeSnapshot(File snapshotDir) throws IOException {
        File snapshotFile = new File(snapshotDir, snapshotFileName);
        if (snapshotFile.exists() && snapshotFile.isFile()) {
            LOGGER.error(
                    "template failed to take snapshot, because snapshot file [{}] is already exist.",
                    snapshotFile.getAbsolutePath());
            return false;
        }
        File tmpFile = new File(snapshotFile.getAbsolutePath() + "-" + UUID.randomUUID());
        templateReadWriteLock.writeLock().lock();
        try (FileOutputStream fileOutputStream = new FileOutputStream(tmpFile);
             BufferedOutputStream outputStream = new BufferedOutputStream(fileOutputStream)) {
            serialize(outputStream);
            outputStream.flush();
            fileOutputStream.flush();
            outputStream.close();
            fileOutputStream.close();
            return tmpFile.renameTo(snapshotFile);
        } finally {
            for (int retry = 0; retry < 5; retry++) {
                if (!tmpFile.exists() || tmpFile.delete()) {
                    break;
                } else {
                    LOGGER.warn(
                            "Can't delete temporary snapshot file: {}, retrying...", tmpFile.getAbsolutePath());
                }
            }
            templateReadWriteLock.writeLock().unlock();
        }
    }

    public void processLoadSnapshot(File snapshotDir) throws IOException {
        File snapshotFile = new File(snapshotDir, snapshotFileName);
        if (!snapshotFile.exists() || !snapshotFile.isFile()) {
            LOGGER.error(
                    "Failed to load snapshot,snapshot file [{}] is not exist.",
                    snapshotFile.getAbsolutePath());
            return;
        }
        templateReadWriteLock.writeLock().lock();
        try (FileInputStream fileInputStream = new FileInputStream(snapshotFile);
             BufferedInputStream bufferedInputStream = new BufferedInputStream(fileInputStream)) {
            // Load snapshot of template
            this.templateMap.clear();
            deserialize(bufferedInputStream);
            bufferedInputStream.close();
            fileInputStream.close();
        } finally {
            templateReadWriteLock.writeLock().unlock();
        }
    }

    @TestOnly
    public void clear() {
        this.templateMap.clear();
    }
}
